Which statement best supports the designation of PAX6 as a master regulatory gene for eye development?

• A It is expressed exclusively in the lens placode after optic cup formation
• B It encodes a secreted morphogen that diffuses across the optic vesicle
• C Its ectopic expression in Drosophila induces extra compound eyes ✓
• D Its deletion converts retinal tissue into cartilage

Explanation

Ectopic Pax6 expression in Drosophila (under the eyeless promoter) generates ectopic compound eyes, demonstrating that Pax6 sits high enough in the ocular gene hierarchy to initiate the whole programme, and this function is conserved from fly to human. PAX6 is a transcription factor expressed in the optic vesicle and surface ectoderm before placode formation, and heterozygous human mutation causes aniridia.

Reference: Gilbert, Developmental Biology, 12th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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